netfilter: x_tables: simplify IS_ERR_OR_NULL to NULL test

Since commit 7926dbfa4bc1 ("netfilter: don't use
mutex_lock_interruptible()"), the function xt_find_table_lock can only
return NULL on an error.  Simplify the call sites and update the
comment before the function.

The semantic patch that change the code is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression t,e;
@@

t = \(xt_find_table_lock(...)\|
      try_then_request_module(xt_find_table_lock(...),...)\)
... when != t=e
- ! IS_ERR_OR_NULL(t)
+ t

@@
expression t,e;
@@

t = \(xt_find_table_lock(...)\|
      try_then_request_module(xt_find_table_lock(...),...)\)
... when != t=e
- IS_ERR_OR_NULL(t)
+ !t

@@
expression t,e,e1;
@@

t = \(xt_find_table_lock(...)\|
      try_then_request_module(xt_find_table_lock(...),...)\)
... when != t=e
?- t ? PTR_ERR(t) : e1
+ e1
... when any

// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 10 insertions, 10 deletions

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index e76ab23a2debd..39004da318e2d 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -805,7 +805,7 @@ static int get_info(struct net *net, void __user *user,
 #endif
 	t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
 				    "arptable_%s", name);
-	if (!IS_ERR_OR_NULL(t)) {
+	if (t) {
 		struct arpt_getinfo info;
 		const struct xt_table_info *private = t->private;
 #ifdef CONFIG_COMPAT
@@ -834,7 +834,7 @@ static int get_info(struct net *net, void __user *user,
 		xt_table_unlock(t);
 		module_put(t->me);
 	} else
-		ret = t ? PTR_ERR(t) : -ENOENT;
+		ret = -ENOENT;
 #ifdef CONFIG_COMPAT
 	if (compat)
 		xt_compat_unlock(NFPROTO_ARP);
@@ -859,7 +859,7 @@ static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
 	get.name[sizeof(get.name) - 1] = '\0';
 
 	t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
-	if (!IS_ERR_OR_NULL(t)) {
+	if (t) {
 		const struct xt_table_info *private = t->private;
 
 		if (get.size == private->size)
@@ -871,7 +871,7 @@ static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
 		module_put(t->me);
 		xt_table_unlock(t);
 	} else
-		ret = t ? PTR_ERR(t) : -ENOENT;
+		ret = -ENOENT;
 
 	return ret;
 }
@@ -898,8 +898,8 @@ static int __do_replace(struct net *net, const char *name,
 
 	t = try_then_request_module(xt_find_table_lock(net, NFPROTO_ARP, name),
 				    "arptable_%s", name);
-	if (IS_ERR_OR_NULL(t)) {
-		ret = t ? PTR_ERR(t) : -ENOENT;
+	if (!t) {
+		ret = -ENOENT;
 		goto free_newinfo_counters_untrans;
 	}
 
@@ -1014,8 +1014,8 @@ static int do_add_counters(struct net *net, const void __user *user,
 		return PTR_ERR(paddc);
 
 	t = xt_find_table_lock(net, NFPROTO_ARP, tmp.name);
-	if (IS_ERR_OR_NULL(t)) {
-		ret = t ? PTR_ERR(t) : -ENOENT;
+	if (!t) {
+		ret = -ENOENT;
 		goto free;
 	}
 
@@ -1404,7 +1404,7 @@ static int compat_get_entries(struct net *net,
 
 	xt_compat_lock(NFPROTO_ARP);
 	t = xt_find_table_lock(net, NFPROTO_ARP, get.name);
-	if (!IS_ERR_OR_NULL(t)) {
+	if (t) {
 		const struct xt_table_info *private = t->private;
 		struct xt_table_info info;
 
@@ -1419,7 +1419,7 @@ static int compat_get_entries(struct net *net,
 		module_put(t->me);
 		xt_table_unlock(t);
 	} else
-		ret = t ? PTR_ERR(t) : -ENOENT;
+		ret = -ENOENT;
 
 	xt_compat_unlock(NFPROTO_ARP);
 	return ret;